This invention relates to a monostable multivibrator.
A conventional monostable multivibrator including MOS FET's (monolithic oxide semiconductor field-effect transistors) is composed of an integrating circuit, an inverter connected to the output terminal of the integrating circuit, a flip-flop, and a transistor on-off controlled by the output of the flip-flop and controlling the discharge of a capacitor of the integrating circuit. In such monostable multivibrator, the controlling transistor conducts to reduce the connecting point of a resistor and the capacitor of the integrating circuit to level "0" when the output of the flip-flop is at level "1". When the reset input to the flip-flop is "1" and its output becomes "0", the capacitor is charged through the resistor, and the output of the inverter gets level "0" if the connecting point exceeds the inversion level of the inverter. By this "0" level output of the inverter, the flip-flop is set to have its output at level "1", therby causing the connecting point to resume level "0".
According to the aforementioned monostable multivibrator, the output of the flip-flop is regarded as the output of the multivibrator. Here the pulse width of the output of the multivibrator is determined by the resistor and capacitor of the integrating circuit and the inverted level of the inverter. The resistor or capacitor may be adjusted externally, whereas the inverted level of the inverter varies widly in accordance with the dispersion in threshold voltage Vth because the MOS FET's are subject to substantial dispersion in the threshold voltage depending on the manufacturing conditions. The range of the level dispersion in the inverter is twice or thrice as large as the pulse width of the output of the multivibrator. Such extensive dispersion presents a great problem, practically.